Vector Network Analyzer model

VNA
UHF

TheVNAuhfis
a Vector Network Analyzer for measuring impedance (magnitude and phase) and
filter transmission in the range of 5 KHz to 1 GHz.

A PC is used to plot parameters, such as: Impedance, SWR, Return Loss, S21
and S11.

The test frequency is generated digitally.

An analog to digital converter digitizes the raw data. This avoids
non-linearity associated with diode detectors, and results in very good
dynamic range and linearity for accurate magnitude and phase measurements.

Resistance and reactance measurements of antennas and discrete
components.

Transmission measurements through filters or networks.

Markers for impedance scans and Smith charts.

Parameters that can be plotted include:

Resistance and reactance for series or parallel equivalent circuits.

Impedance magnitude and phase angle.

SWR

Return loss

Two port network transmission (S21, magnitude and phase).

S11 and S21 can be plotted at the same time.

Cable length, impedance, loss, and velocity factor

Distance to fault (open or short)

TDR (Time Domain Reflectometry) plots

Smith chart displays (featuring phase rotation and zoom)

Band scan to check for interfering signals

Quartz crystal parameter measurements

Preprogrammed functions, such as tuning a ¼ WL stub, and many more

I/O expansion port for accessories (digital and analog)

Calibration loads are included

No internal adjustments

Optically isolated USB interface to PC

Impedance measurements can
range up to 10K ohms. The sign of the phase angle indicates either
inductive or capacitive reactance without ambiguity.

The RF generator can also be used as a signal source for testing
receivers. The frequency is very stable and it can be calibrated to WWV.

Digitized data is sent to the PC via an optically isolated USB port.
Power for theVNAuhfcan
be obtained from a small DC power supply or a battery. With a laptop
computer, the unit is quite small and portable. Measurements can be made
at ground level and translated as if they were at the antenna feedpoint by
using the refer to antenna function.

The impedance at the antenna itself can be read with theVNAuhflocated
in the shack at the receiving/transmitting end of the coax. The cable can
be any length. The cable's impedance and loss characteristics are
determined by a simple calibration procedure and the antenna's impedance
is then plotted directly during the scan.

Numeric values can be read from the graph data using the
mouse-controlled cursor.

The scan data can be saved to disk or printed to compare before and
after results. It can also be imported into spreadsheet programs for
further analysis.

Note - CIRCUITS AND PROCEDURES used by
this antenna analysis system are covered by US Patent No. 7,629,795

VNAuhf scan of a 70cm Notch Filter made with an Open Stub of RG316
coax

COMPARISON WITH THE VNA2180

TheVNAuhfis
not a replacement for the VNA2180. The VNA2180 will continue in
production.

Parameter

VNAuhf

VNA2180

Frequency Range

5 kHz to 1 GHz

5 kHz to 180 MHz

Output signal into 50 ohms

0.035 Vrms (-13dBm)

0.5 Vrms (+7dBm)

Max interference input
while measuring

0.1Vrms (-7dBm)

1.4 Vrms (+16dBm)

Programmable output level

Yes

Yes

Two ports for filter testing

Yes

Yes

Program port for accessories

Yes

Yes

Antenna & component testing

Yes

Yes

Trace overlays of a Cellular duplexer measurement with an HP8722 VNA
and the VVN uhf

VNA uhf Return loss in blue.
S21 (transmission gain) in Green

8722 Return loss in purple.
S21 (transmission gain) in
light purple

The VNAuhf is now available and includes calibration loads,
cables and a power supply for 120V operation.

The VNAUHFDX is also available, but with a "global power supply"
for use outside North America.